Home base stations (e.g. home NodeBs or home eNodeBs), local-area base stations (e.g. local-area NodeBs or local-area eNodeBs), femto eNodeBs or any other type of home access device (in the following referred to as “HNB”) or local-area access device (in the following referred to as “LNB”) have become a widely discussed topic. As an example, when deployed in homes and offices, HNBs allow subscribers to use their existing handsets—in a building—with significantly improved coverage and increased broadband wireless performance. Moreover, Internet Protocol (IP) based architecture allows deployment and management in virtually any environment with broadband Internet service.
With the introduction of High Speed Downlink Packet Access (HSDPA) in various commercial networks, operators noticed quite substantial date rate, i.e. capacity, consumption of single users. Those are in most cases users staying at home and using a HSDPA data card or the like for substantial Internet surfing like downloading movies etc. However, existing mobile communication systems (e.g. Global System for Mobile communications (GSM), Wideband Code Division Multiple Access (WCDMA/HSDPA) are not optimal suited for such home-based application, as those were developed and defined under the assumption of coordinated network deployment, whereas HNBs are typically associated with uncoordinated and large scale deployment.
In HNB scenarios, it is generally assumed that an end user is buying a cheap (Wireless Local Area Network (WLAN) like) product and also installs this physical entity at his home. Such a HNB would then provide coverage/service to the terminals registered by the owner of the HNB. Still the HNB would use the same spectrum owned by the operator and as such at least partly the spectrum the operator is using to provide macro cell coverage to the area where the HNB is located in.
Moreover, sharing and pooling properties may be provided in the core network, where several operator's core networks are attached to the same access node or foreign mobile terminal devices or user equipments (UEs) roam into a HNB or LNB nominally “owned” by a certain operator.
A self-organization network (SON) is based on a network concept with functionalities enabling and supporting capabilities in which certain network entities can change or can be changed in their configuration without manual intervention. This concept, as such, is rather broad, ranging from a self-tuning of certain network configuration parameters for performance optimization purposes to a self-reorganizing of certain parts of the network affecting network structures and operations. In this regard, enabling plug-and-play access devices in a multi-operator spectrum-sharing environment is one of the ultimate challenges. This may be advantageous for possible mass-deployment of HNBs or LNBs in LTE and IMT-A systems.
Moreover, flexible spectrum use (FSU) refers to any spatially and/or temporarily varying use of a radio spectrum, i.e., not based on exclusive harmonized spectrum assignments for each system and operator. The term “radio spectrum” herein can be considered as a multidimensional entity, not just about the carrier frequency and system bandwidth. Dimensions of radio spectrum may include for example space, time, polarization, frequency channel, power of signal transmission and interference. The static, command-and-control management of spectrum has led to barriers to accessing the spectrum in various dimensions. FSU aims to break these barriers in one or more of the dimensions. This also includes the so-called spectrum sharing (SS). SS refers to situations in which different radio (sub-) systems utilize the same part of spectrum in a coordinated or uncoordinated manner. These radio (sub-) systems, typically, are based on similar technology and offer similar services, e.g., different operators sharing the same spectrum by utilizing dynamic channel assignment from a common pool of channels. However, SS between a primary system, such as a fixed satellite service (FSS) system, and a secondary system, such as an advanced mobile cellular system which is allowed to use the spectrum resources of the FSS system wherever and whenever tolerable, is a probable scenario.
However, in connection with the above SON and FSU concepts, inter-cell and co-channel interference problems affecting the operation of individual neighboring cells and, in particular, common and control channels which are essential to the cell operation and may have predefined semi-static allocation, must be resolved. These problem are even more crucial when considering plug-and-play nature of HNBs and/or LNBs in SON in single RAT multi-operator spectrum-sharing environments. Furthermore, initial setup, reset or removal of a plug-and-play HNB or LNB must ensure minimum impact on the operating network environment, i.e., avoiding chain-reaction of forced network reconfigurations over a sizable number of cells around the given HNB or LNB.
The development of SON for advanced mobile cellular networks has been so far focusing on self-optimization aspects with centralized network planning and operation and maintenance (O&M) support, rather than self-organization. The aspects and impacts of multi-operator environment in which different networks of different operators can use the same radio access technology and be deployed in overlapping spectrum and service area, have not been addressed yet.
Furthermore, SON methods and mechanisms which have been proposed for 3GPP LTE are involved around the so-called automatic neighbor relation (ANR) concept and optimization of neighbor cell list (NCL). These, in turn, are based on O&M network configuration and terminal measurements of neighbor cells.